Source google image: https://www.installation-renovation-electrique.com/images/schemas%20de%20principe/plan%20architectural%20double%20va%20et%20vient%202.jpg
Schema electrique double interrupteur va et vient
Source google image: https://www.installation-renovation-electrique.com/images/schemas%20de%20principe/plan%20architectural%20double%20va%20et%20vient%202.jpg